MEXICO CITY, Feb 24 (Reuters) - Mexican annual inflation cooled to a nearly 4-year low, just above the central bank's 3 percent target, in the first half of February, even as a weaker peso threatened to push up consumer prices in Latin America's second biggest economy.

Inflation in the 12 months through mid-February eased to 3.04 percent, data from Mexico's national statistics office showed on Tuesday, below the 3.07 percent in the full month of January and the 3.09 percent expected in a Reuters poll.

The figure was the lowest since the second half of March 2011, according to national statistics agency data.

The bank held its benchmark interest rate at a record low of 3 percent last month, and is expected to hike rates around the time the U.S. Federal Reserve lifts borrowing costs.

Tumbling oil prices have hammered Mexico's peso, which has weakened to near 6-year lows.

Mexico is a top crude exporter to the United States and the government relies on revenues from the state-run oil company Pemex to fund about a third of its budget.

Consumer prices rose 0.11 percent in the first half of February, compared with expectations for a 0.16 percent rise, as tomato, bakery goods and onion prices fell.

Core prices, which strip out some volatile food and energy costs, climbed 0.28 in that half-month, below expectations of a 0.17 percent rise. (Reporting by Alexandra Alper; Editing by Simon Gardner and W Simon)